package com.ctrip.framework.apollo.configservice.util;

import com.ctrip.framework.apollo.common.entity.AppNamespace;
import com.ctrip.framework.apollo.configservice.service.AppNamespaceServiceWithCache;
import com.ctrip.framework.apollo.core.ConfigConsts;
import com.google.common.base.Joiner;
import com.google.common.base.Strings;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;
import org.springframework.stereotype.Component;

import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

@Component
public class WatchKeysUtil {

    private static final Joiner STRING_JOINER = Joiner.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR);
    private final AppNamespaceServiceWithCache appNamespaceService;

    public WatchKeysUtil(final AppNamespaceServiceWithCache appNamespaceService) {
        this.appNamespaceService = appNamespaceService;
    }

    /**
     * Assemble watch keys for the given appId, cluster, namespace, dataCenter combination
     */
    public Set<String> assembleAllWatchKeys(String appId, String clusterName, String namespace, String dataCenter) {
        Multimap<String, String> watchedKeysMap = assembleAllWatchKeys(appId, clusterName, Sets.newHashSet(namespace), dataCenter);
        return Sets.newHashSet(watchedKeysMap.get(namespace));
    }

    /**
     * Assemble watch keys for the given appId, cluster, namespaces, dataCenter combination
     *
     * @return a multimap with namespace as the key and watch keys as the value
     */
    public Multimap<String, String> assembleAllWatchKeys(String appId, String clusterName, Set<String> namespaces, String dataCenter) {
        Multimap<String, String> watchedKeysMap = assembleWatchKeys(appId, clusterName, namespaces, dataCenter);

        // Every app has an 'application' namespace
        if (!(namespaces.size() == 1 && namespaces.contains(ConfigConsts.NAMESPACE_APPLICATION))) {
            Set<String> namespacesBelongToAppId = namespacesBelongToAppId(appId, namespaces);
            Set<String> publicNamespaces = Sets.difference(namespaces, namespacesBelongToAppId);

            // Listen on more namespaces if it's a public namespace
            if (!publicNamespaces.isEmpty()) {
                watchedKeysMap.putAll(findPublicConfigWatchKeys(appId, clusterName, publicNamespaces, dataCenter));
            }
        }

        return watchedKeysMap;
    }

    private Multimap<String, String> findPublicConfigWatchKeys(String applicationId,
                                                               String clusterName,
                                                               Set<String> namespaces,
                                                               String dataCenter) {
        Multimap<String, String> watchedKeysMap = HashMultimap.create();
        List<AppNamespace> appNamespaces = appNamespaceService.findPublicNamespacesByNames(namespaces);

        for (AppNamespace appNamespace : appNamespaces) {
            // check whether the namespace's appId equals to current one
            if (Objects.equals(applicationId, appNamespace.getAppId())) {
                continue;
            }
            String publicConfigAppId = appNamespace.getAppId();
            watchedKeysMap.putAll(appNamespace.getName(), assembleWatchKeys(publicConfigAppId, clusterName, appNamespace.getName(), dataCenter));
        }

        return watchedKeysMap;
    }

    private String assembleKey(String appId, String cluster, String namespace) {
        return STRING_JOINER.join(appId, cluster, namespace);
    }

    private Set<String> assembleWatchKeys(String appId, String clusterName, String namespace, String dataCenter) {
        if (ConfigConsts.NO_APPID_PLACEHOLDER.equalsIgnoreCase(appId)) {
            return Collections.emptySet();
        }
        Set<String> watchedKeys = Sets.newHashSet();

        // watch specified cluster config change
        if (!Objects.equals(ConfigConsts.CLUSTER_NAME_DEFAULT, clusterName)) {
            watchedKeys.add(assembleKey(appId, clusterName, namespace));
        }

        // watch data center config change
        if (!Strings.isNullOrEmpty(dataCenter) && !Objects.equals(dataCenter, clusterName)) {
            watchedKeys.add(assembleKey(appId, dataCenter, namespace));
        }

        // watch default cluster config change
        watchedKeys.add(assembleKey(appId, ConfigConsts.CLUSTER_NAME_DEFAULT, namespace));
        return watchedKeys;
    }

    private Multimap<String, String> assembleWatchKeys(String appId, String clusterName,
                                                       Set<String> namespaces,
                                                       String dataCenter) {
        Multimap<String, String> watchedKeysMap = HashMultimap.create();

        for (String namespace : namespaces) {
            watchedKeysMap.putAll(namespace, assembleWatchKeys(appId, clusterName, namespace, dataCenter));
        }

        return watchedKeysMap;
    }

    private Set<String> namespacesBelongToAppId(String appId, Set<String> namespaces) {
        if (ConfigConsts.NO_APPID_PLACEHOLDER.equalsIgnoreCase(appId)) {
            return Collections.emptySet();
        }
        List<AppNamespace> appNamespaces = appNamespaceService.findByAppIdAndNamespaces(appId, namespaces);

        if (appNamespaces == null || appNamespaces.isEmpty()) {
            return Collections.emptySet();
        }

        return appNamespaces.stream().map(AppNamespace::getName).collect(Collectors.toSet());
    }
}
